Since their introduction, communication satellites provide a platform for communications over links extending over a long range having a very wide area coverage. Satellites provide an excellent solution for applications like broadcasting, video transmission, telephony, data trunking and others.
For other applications, such as sensor networks or remote infrastructure monitoring such as water, gas and electricity facilities metering, satellites may provide an excellent solution for the communications needs associated with these applications. The very large coverage area of a satellite enables such a system to use a single hub in which data from a continent size region can be collected. The spectral requirements from such systems, being mainly for communications at a relatively very low rate, make it possible to operate with a limited amount of satellite spectral resources, even under very poor SNR conditions. On the other hand, in many cases, equipment size and power requirements present an obstacle for implementing a satellite communication terminal, which typically has a relatively large footprint from both size and power aspects.
The requirement for a small size terminal implies directly that a small antenna and small electronic equipment size, should be used. A smaller antenna affects the link budget, yet, the fact that the data rate requirement, and consequently the respective bandwidth requirement, are both low, makes it possible to still be able to operate in a very low Signal to Noise ratio (SNR) conditions. The VLSNR mode of the new DVB-S2X standard enables operation in an SNR as low as −10 dB.
Therefore, the problem which the present invention seeks to solve is how to provide an air interface that enables operating under conditions where the SNR is even lower than the −10 dB value referred to above. Such an extremely low SNR is referred to herein throughout the specification and claims as Extremely Low Signal to Noise Ratio (“ELSNR”). In other words, how to enable operation under conditions where the SNR is for example as low as say −30 dB, at the expanse of the data rate.